Why holding your stretches longer isn’t just about patience, it’s about neuroscience
You’re in a deep hamstring stretch, feeling that familiar pull in the back of your leg. You know you should hold it longer, but your body is screaming at you to stop. Every muscle fibre feels like it’s resisting, fighting against you going any deeper.
Here’s what’s actually happening: your body isn’t being stubborn or difficult. It’s trying to protect you. And the system that protects is called the stretch reflex. Understanding how the stretch reflex works is the difference between fighting your body and working with it. Once you know what’s happening at a neurological level, you can use that knowledge to actually get further in your stretches, safely and effectively.
Let’s break down the science behind why your muscles resist when you stretch, and more importantly, how to make that resistance work for you instead of against you.
What is the stretch reflex?
By understanding how our body moves from the inside, we can make the most of our stretches. Many of our movements are controlled by the brain talking to the body. If you want your hand to open and close its fingers, your brain tells your fingers what to do. But the brain isn’t the boss of all our body movements. Some of our body movements are primitive actions, like heart functions, breathing, and reflexes. These actions happen automatically, without conscious thought.
The stretch reflex is one of those automatic protective mechanisms. It’s a pre-programmed response by your body to a stretch stimulus in the muscle. Research shows that when a muscle spindle is stretched, an impulse is immediately sent to the spinal cord, and a response to contract the muscle is received. This happens incredibly fast, within 1 to 2 milliseconds, because the impulse only has to travel to the spinal cord and back, not all the way to the brain.
How muscle spindles control the stretch reflex
To understand how to use the stretch reflex to your benefit, we need to look at your body’s mechanics. Within your muscle fibres are sensory receptors called muscle spindles. A muscle spindle is wired to react in a predetermined way, just like those primitive actions we mentioned before.
Think of a muscle spindle as a thread spiralled around muscle fibres near the muscle belly. As the muscle lengthens or stretches, it pulls on the spindle, causing it to lose its spiral shape and also stretch. This signals the muscle to contract (after which the spiral regains its shape), protecting the muscle from being overstretched.
When a muscle stretches, the muscle spindle talks to the spinal cord. The spinal cord, in turn, tells the muscle to contract and resist the stretch. This process is called the spinal cord reflex arc, and it exists to protect the muscle from tearing. Research published in Current Biology explains that muscle spindles detect changes in muscle length and the speed of stretching, then send signals directly to motor neurons innervating the same muscles, leading to muscle contraction.
The strength of your muscle’s response is determined by the speed at which the stretch occurs. When a stretch happens more rapidly, the spindle stimulates a greater firing frequency of the motor neuron, and the more forceful the muscle contraction is in response. This is primarily a protective mechanism to avoid potential damage when a muscle is rapidly stretched beyond its limit.
Why your body panics when you stretch
The spinal cord reflex arc may prevent a deeper stretch because it essentially panics about needing to protect you. Your body doesn’t know the difference between you intentionally stretching your hamstring and you accidentally stepping in a pothole and rolling your ankle. All it knows is that muscle fibres are lengthening quickly, and its job is to stop that from going too far.
This is actually brilliant design when it comes to injury prevention. If you trip or stumble, the stretch reflex kicks in within milliseconds to contract the stretched muscles and prevent you from tearing something. But when you’re intentionally trying to increase your flexibility, that same protective mechanism can feel like it’s working against you.
How to work with this reflex and not against it
When you hold a stretch for a prolonged amount of time, the muscle spindle comes to terms with what you’re doing and calms down a bit. This is why it’s often suggested to hold a stretch for at least 30 to 60 seconds. The longer you hold, the more your nervous system realises you’re not in danger, and the more it allows the muscle to relax into the stretch.
But you can actually quicken this process by using a few specific techniques:
Ease in and out of the motion
You can reduce the stretch reflex by gently pulsing in and out of a stretch rather than forcing yourself into the deepest position immediately. This teaches your nervous system that the movement is safe and controlled.
Activate the opposite muscle group
By contracting the antagonist muscle (the muscle that does the opposite action), you can diminish the spinal cord reflex arc. For example, in a hamstring stretch like a half split, engaging your quadriceps muscle tells your nervous system to relax your hamstrings. This is called reciprocal inhibition, and it’s one of the most effective ways to work with your body’s neurological wiring instead of fighting it.
Breathe deeply and slowly
Your breath directly affects your nervous system. Slow, deep breathing signals to your body that you’re safe, which helps reduce the stretch reflex response. This is why I’m always reminding you to breathe in my classes. It’s not just about getting oxygen to your muscles. It’s about telling your nervous system to relax.
Hold stretches longer
Research has shown that static stretches held for longer durations (45 to 60 seconds or more) allow the muscle spindle sensitivity to decrease, which reduces the reflexive muscle contraction. The longer you hold, the more your body adapts to the new range of motion.
The Golgi tendon organ: your flexibility secret weapon
There’s another proprioceptor that plays a role in flexibility, and it works almost opposite to the muscle spindle. It’s called the Golgi tendon organ (GTO), and it’s located where your muscle connects to your tendon.
When a muscle is under excessive tension (either from stretching or contracting), the GTOs are activated and cause the muscle to relax by interrupting its contraction. This process is called autogenic inhibition. Two important proprioceptors, the GTO and muscle spindle, work together reflexively to regulate muscle stiffness.
This is why holding a stretch for an extended period (longer than 30 seconds) eventually feels easier. Your muscle spindles start to calm down, and your GTOs kick in to help the muscle relax. You’re not just stretching the muscle. You’re retraining your nervous system’s response to that stretch.
How to stretch smarter
So what does all this science actually mean for your flexibility practice? Here’s how to apply it:
Don’t rush into your deepest stretch
Ease in gradually. Give your muscle spindles time to adjust to the lengthening before you push deeper.
Use reciprocal inhibition
In a lunge with a back bend, engage your glutes and quads on the front leg whilst you’re stretching. In a hamstring stretch, contract your quads. This tells your nervous system to release the muscle you’re trying to stretch.
Hold stretches for at least 45 to 60 seconds
This gives your muscle spindles time to calm down and your GTOs time to activate. Shorter holds won’t give your nervous system enough time to adapt (unless you have hypermobility, then stick to 30 seconds max and do 2-3 reps).
Breathe consciously
Inhale to prepare, exhale to sink deeper. Use your breath to signal safety to your nervous system.
Be consistent
Your nervous system adapts through repetition. The more frequently you stretch (with proper technique), the more your body learns that these ranges of motion are safe, and the less your stretch reflex will fight you over time.
Why this matters for your flexibility goals
Understanding the stretch reflex isn’t just nerdy science trivia. It’s the key to making actual, sustainable progress in your flexibility training. When you know why your body resists certain stretches, you can use specific techniques to work with that resistance instead of trying to force your way through it.
Forcing a stretch before your nervous system is ready is how people get injured. Working with your stretch reflex, giving it time to adapt, and using strategies like reciprocal inhibition is how you build flexibility that actually lasts. Your body is smarter than you think. It’s designed to protect you. When you understand how that protection works, you can gently teach it that deeper ranges of motion are safe, and you’ll make progress without the fight.
If you want guided classes that incorporate these neuroscience principles into practical stretching routines, The Garden has everything you need. Every class is designed with your nervous system in mind, using cues that help you work with your stretch reflex instead of against it.
Train your brain. Trust your body. Get further.
